vc: switch to fixed_size_llseek()

Signed-off-by: Al Viro <[e-mail]>

drivers/tty/vt/vc_screen.c

···
 	console_unlock();
 	if (size < 0)
 		return size;
-	switch (orig) {
-		default:
-			return -EINVAL;
-		case 2:
-			offset += size;
-			break;
-		case 1:
-			offset += file->f_pos;
-		case 0:
-			break;
-	}
-	if (offset < 0 || offset > size) {
-		return -EINVAL;
-	}
-	file->f_pos = offset;
-	return file->f_pos;
+	return fixed_size_llseek(file, offset, orig, size);
 }